Add uma stats to help evaluate the impact of changes to the quota allocation logic.

content/browser/service_worker/service_worker_disk_cache.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/service_worker/service_worker_disk_cache.h"
 
 namespace content {
 
 ServiceWorkerDiskCache::ServiceWorkerDiskCache()
-    : AppCacheDiskCache(true /* use_simple_cache */) {}
+    : AppCacheDiskCache(true /* use_simple_cache */) {
+  uma_name_ = "DiskCache.ServiceWorker";
+}
 
 ServiceWorkerResponseReader::ServiceWorkerResponseReader(
     int64_t resource_id,
     const base::WeakPtr<AppCacheDiskCacheInterface>& disk_cache)
     : AppCacheResponseReader(resource_id, disk_cache) {}
 
 ServiceWorkerResponseWriter::ServiceWorkerResponseWriter(
     int64_t resource_id,
     const base::WeakPtr<AppCacheDiskCacheInterface>& disk_cache)
     : AppCacheResponseWriter(resource_id, disk_cache) {}
 
 ServiceWorkerResponseMetadataWriter::ServiceWorkerResponseMetadataWriter(
     int64_t resource_id,
     const base::WeakPtr<AppCacheDiskCacheInterface>& disk_cache)
     : AppCacheResponseMetadataWriter(resource_id, disk_cache) {}
 
 }  // namespace content